So this just happened recently; I went to send an email from my Yahoo account to my server's email and mailer-daemon replies saying, 'Remote host said: 550 #5.1.0 Address rejected firstname.lastname@example.org
[RCPT_TO] (123 is placeholder). I have a domain name hosted through GoDaddy but I route the MX Records etc. from there to mt server. I'm kinda stuck on what to do next. I can send emails fine from my email, but sending TO it is the part not working. Thanks!